﻿#region Copyright & License

//
// Author: Ian Davis <ian.f.davis@gmail.com> Copyright (c) 2007-2008, Ian Davs
//
// Portions of this software were developed for NUnit. See NOTICE.txt for more
// information. 
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
//

#endregion

#region Using Directives

using System;
using Ensurance.Properties;

#endregion

namespace Ensurance.Constraints
{
    /// <summary>
    /// Summary description for BetweenConstraint.
    /// </summary>
    public class RangeConstraint<T> : Constraint<T>
    {
        private IComparable _high;
        private bool _includeHigh = false;
        private bool _includeLow = true;
        private IComparable _low;

        /// <summary>
        /// Initializes a new instance of the <see cref="RangeConstraint"/>
        /// class.
        /// </summary>
        /// <param name="low">The low.</param>
        /// <param name="high">The high.</param>
        /// <param name="includeLow">if set to <c>true</c> [include low].</param>
        /// <param name="includeHigh">if set to <c>true</c> [include high].</param>
        public RangeConstraint(IComparable low, IComparable high, bool includeLow, bool includeHigh)
        {
            _low = low;
            _high = high;
            _includeLow = includeLow;
            _includeHigh = includeHigh;
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="RangeConstraint"/>
        /// class.
        /// </summary>
        /// <param name="low">The low.</param>
        /// <param name="high">The high.</param>
        /// <param name="inclusive">if set to <c>true</c> [inclusive].</param>
        public RangeConstraint(IComparable low, IComparable high, bool inclusive)
            : this(low, high, inclusive, inclusive)
        {
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="RangeConstraint"/>
        /// class.
        /// </summary>
        /// <param name="low">The low.</param>
        /// <param name="high">The high.</param>
        public RangeConstraint(IComparable low, IComparable high)
            : this(low, high, true, false)
        {
        }

        /// <summary>
        /// Test whether the constraint is satisfied by a given value
        /// </summary>
        /// <param name="actual">The value to be tested</param>
        /// <returns>True for success, false for failure</returns>
        public override bool IsSatisfiedBy(T actual)
        {
            Actual = actual;

            if (ReferenceEquals(actual, null))
            {
                return false;
            }

            System.Type actualType = actual.GetType();
            if (actualType != _low.GetType() || actualType != _high.GetType())
            {
                return false;
            }

            int lowCompare = _low.CompareTo(actual);
            if (lowCompare > 0 || !_includeLow && lowCompare == 0)
            {
                return false;
            }

            int highCompare = _high.CompareTo(actual);
            return highCompare > 0 || _includeHigh && highCompare == 0;
        }

        /// <summary>
        /// Write the constraint description to a MessageWriter
        /// </summary>
        /// <exception cref="ArgumentNullException">if the message writer is null.</exception>
        /// <param name="writer">The writer on which the description is displayed</param>
        public override void WriteDescriptionTo(IMessageWriter writer)
        {
            if (writer == null)
            {
                throw new ArgumentNullException("writer");
            }

            writer.WritePredicate(Resources.Between);
            writer.WriteExpectedValue(_low);
            writer.WriteConnector(Resources.And);
            writer.WriteExpectedValue(_high);
        }
    }
}
